The Beryl project has often been criticised as being nothing more than eyecandy for the sake of eyecandy. However, there are numerous features in Beryl which could improve usability and workflow. In this series of three articles, some of the new usability features in Beryl 0.2.0 are highlighted and explained (article I, article II, and article III).

-Does anyone know what is faster? (XGL/AIGLX) for use with beryl? So far beryl+aiglx doesnt even come a little close to the performance i had with compiz+xgl on my geforce mx 4400, so i'm wondering if i'm doing something wrong.
-Does xvideo work in any way in xgl/aiglx? so far all videoplayers are extremely slow in fullscreen mode..

Yeah, it seems that AIGLX *is* slower than XGL...at least that's the impression I get on my older desktop box. I'm not sure how it translates in numbers, to IIRC there is a "performance" plugin in Beryl that you can activate to get info on how well things are running.

In my experience, AIGLX has been much faster than XGL. On Intel graphics chipsets, it's no contest. AIGLX absolutely hums on Intel. On NVIDIA, as long as you've got the latest 9xxx series binary drivers, AIGLX works very nicely. I found moving from XGL to AIGLX on NVIDIA fixed all my video playback issues (including xv).

On NVIDIA, as long as you've got the latest 9xxx series binary drivers, AIGLX works very nicely.

Are these the new beta drivers? I don't know, I'm using AIGLX with NVIDIA on my desktop, and it doesn't feel as fast as XGL on my laptop, but perhaps my setup is suboptimal. I'll check it out tonight (I barely use my desktop PC anymore, so I haven't taken the time to update it in a while).

Does anyone know what is faster? (XGL/AIGLX) for use with beryl? So far beryl+aiglx doesnt even come a little close to the performance i had with compiz+xgl on my geforce mx 4400, so i'm wondering if i'm doing something wrong.

Having used both, I say any perceptible performance difference in terms of desktop responsiveness is negligible.

Xgl does extract a penalty in terms of resources, but on modern machines, again it's probably imperceptible. On my old P3/1.13G laptop, I could measure it as being reported as an extra 8-9% CPU Utilization, with my Turion x2, it's maybe an extra 1% if that.

Where Xgl falls down compared to AIGLX is that it's implementation prevents GL applications from having direct access to the hardware. So any GL-based apps running under XGL have to use the indirect GL-X libraries for rendering, which is the reason anyone running glxinfo under an XGL desktop will find direct rendering disabled; this results in apps like GoogleEarth or even the openGL screensavers as being anywhere from unusable to roughly usable, depending upon hardware. For gaming, forget it. Many people that rely on GL-apps but want their Xgl have resorted to hacks and workarounds, such as launching a separate nested X server alongside Xgl for rendering GL apps. That starts to get really really ugly.

The AIGLX implementation doesn't interfere with the ability for GL-apps to render directly, so I've found the difference between using both to be night and day. Even if it's not an issue of the actual performance of the window rendering, it makes a monumental difference if you use any GL-based apps. The aforementioned GoogleEarth (I fall back to this because it's a reasonably intensive GL-based app and I'm not a gamer) works as well under my AIGLX-rendered desktops as standard X desktops.

Now, I should probably qualify that by pointing out I'm not actually using AIGLX, since beryl links directly to the nvidia driver libraries and not Xorg's, for rendering. I would expect that to lead to improved performance, but I'm not an engineer so am not qualified to say definitively.

The biggest advantage of Xgl over AIGLX that I can see is universality; theoretically Xgl should work with any graphics subsystem capable of accelerated 3d rendering in Xorg, while AIGLX requires special driver support. The biggest drawback is the current incompatibility with 3d-applications under Xgl. That's not an issue for many people though.